Recall that in law, you're mostly dealing with people who have a problem. Yes, there is some transactional work, but it is usually either low-paying or at least somewhat adversarial. Will dealing with miserable people all day make you miserable? If so, skip law.

For programming, if you follow the path that LW recommends, you should be able to tell within a month or two whether you like it enough to continue.

I would be surprised to learn that market research pays well. I just Googled, and this was the first hit that had salary data. It's not terrible, but any of the other careers (except law, if you're not in the top tier) will do better. That's not surprising; there are a ton of psychology and political science majors produced every year.